Improving the level of water quality and plant species diversity in the reservoir accumulating natural effluents from the reclaimed uranium-containing industrial waste dump.

Due to the need to achieve the principles of sustainable development and to understand the processes of formation of phytocenoses in areas that were adversely affected by the industrial impact, this study assessed the condition of the Grachevsky uranium mine (Kazakhstan), which underwent conservation procedures about 25 years ago. The purpose is to determine the level of water quality and phytocenosis of the shores of the reservoir accumulating natural effluents from reclaimed dumps and anthropogenic sites of a uranium mine, as well as quality indicators and toxicology. The assessment included a qualitative research method (analysis of documents) to determine agro-climatic conditions and empirical methods of collecting information. The authors studied the intensity of ionizing radiation of the gamma background of the water surface of the reservoir (and sections of the shoreline and territories adjacent to the reservoir), and hydrochemical parameters of the waters of the reservoir, and performed a description of the botanical diversity. The vegetation cover of the sections of the reservoir shore is at different stages of syngenesis and is represented by pioneer groupings, group thicket communities, and diffuse communities. Favorable ecological conditions for the settlement and development of plants develop within the shores of the reservoir. The intensity levels of ionizing radiation do not exceed the maximum permissible levels and practically do not affect the formation of phytocenoses. An anthropogenically modified dry meadow with the participation of plants typical of the steppe zone has been formed on the floodplain terrace. Concerning the indicators of quality and toxicology of this reservoir, the water can be used for household and drinking purposes under the condition of prior water treatment. It can be concluded that a high level of natural purification of the reservoir waters occurred within twenty years after the reclamation of the uranium mine.

Fractionation of some natural radionuclides in Albic Retisol.

In the present work, the fractionation of heavy natural radionuclides was investigated in Albic Retisol in the Moscow region of Russia. Fractionation was performed using the Pavlotskaya method. 238U and 232Тh were measured via inductively coupled plasma mass spectrometry and 226Ra was measured using an alpha-radiometer that considered the decay of Ra isotopes and accumulation of the resulting decay-related products. Results showed that the potential mobility of radionuclides during migration to adjacent environments and biological availability to plants follows the order 226Ra > 238U > 232Тh. The depletion of 226Ra in the humus horizon A was manifested as a decrease in the 226Ra/238U activity ratio to below 1 in fraction F4.1 (associated with organic matter) and fraction F4.2 (acid-soluble compounds). The profile distribution of 226Ra and 238U in the residual fraction revealed the genetic relationship between these radionuclides. Mobile compounds of 238U and 232Th leached into the lower part of the profile where they became fixed, mainly as the components of fractions associated with organic matter and crystallized iron oxides. A similar profile distribution was found for 238U, 232Тh, and Fe in the acid-soluble fraction associated with crystallized iron oxides. The results obtained herein can form the basis for regulating the mobility and bioavailability of radionuclides to ameliorate their adverse effects on plants and soil ecosystems.

[Simulation of Radionuclide Behaviour in Terrestrial Ecosystems in Studies of Ecological Consequences of Accident at Chernobyl NPP].

The article analyzes the results of using the imitation modeling method for the study, prediction and recon- struction processes of radionuclide. behaviour in terrestrial ecosystems after the Chernobyl accident. Also discussed are some additional issues associated with the application of this method and perspectives of radio- ecological modeling.

[Distribution of 137Cs, 90Sr and their chemical analogues in the components of an above-ground part of a pine in a quasi-equilibrium condition].

The additional study of the distribution of radioactive isotopes of caesium and strontium and their chemical analogues in the above-ground components of pine in the remote from the accident period was carried out. The results of the research confirmed the existence of analogy in the distribution of these elements on the components of this type of wood vegetation in the quasi-equilibrium (relatively radionuclides) condition. Also shown is the selective possibility of using the data on the ash content of the components of forest stands of pine and oak as an information analogue.

[Role of macromycetes as accumulators of 137Cs in forest ecosystems].

One of the problems of forest radioecology concerning the role of macromycetes in accumulation of caesium radionuclides in ground ecosystems is discussed in the paper. The main positions of the researchers working in this area are stated, and their arguments relating to the given problem are compared. The findings of the analysis of the literary data on a 137Cs content in fruit bodies and mycelium of fungi are represented. Similar findings on the behaviour of its chemical analog--potassium, studies of fungi physiology and effects of physicochemical processes in soils on the behaviour of this radionuclide are also used when examining the behaviour of 137Cs in fungi.

[The comparative analysis of 137Cs, 40K, K, 90Sr and Ca allocation in builders of an ground part of wood plants in a quasi-equilibrium condition].

The examinations of allocation of radioactive isotopes of caesium and of strontium and of their chemical analogs in a stand of forest ecosystems are carried out. By results of examinations and analysis of literary data the presence of analogy in allocation of these elements on builders in quasi-balanced (concerning radionuclides) state was confirmed. The question about the opportunity of use of data about behaviour of K and of Ca is considered at an explanation of the mechanisms of redistribution of 137Cs and of 90Sr in wood plants and for buildup of mathematical models of behaviour of datas of radionuclides in ground ecosystems.

[The results of computerization of studies of ecological consequences of the accident on the Chernobyl Nuclear Power Plant for terrestrial ecosystems].

In the paper some results of application of information and calculation technologies in researches of ecological consequences of accident on Chernobyl NPP are brought. The effectiveness of a computerization of investigations is scored. Technical and information component isselected. The singularities of application of the methodology of computerization in radioecological researches are considered. The special attention is given to integration of knowledge accumulated in the form of information materials, databases, mathematical models. The browse of the series of radioecological information and of informational-prognostic systems constructed from the moment of accident is made. As an example of successful usage of a computerization in radioecological researches provided by small scientific collectives experience of MSU division of radioecology and ecotoxicology are considered.

[Imitation model of 90Sr behaviour in the soil and stand of pine forest].

The algorithm of display of 90Sr behaviour mechanisms in forest ecosystems by method of imitating modeling is developed. Distinctive features of algorithm: the 90Sr contents in vegetation is subdivided into two parts (outside and internal pollution), which dynamics is considered separately; dynamics of a radionuclide is considered in connection with dynamics of organic substance; it is supposed, that 90Sr behaviour in plants is similar to Ca behaviour; the biological availability 90Sr contained in a soil, is integrated function of time and physico-chemical properties of the given soil. On the basis of offered algorithm the model is constructed which is used for realization of a number of numerical experiments, including reconstruction of a situation of pollution of forest ecosystem on grey forest soils in result of Kyshtym accident. The quantitative estimations of intensity of 90Sr redistribution between stand components and soil are received. The modern problems of creation of prognostication models of 90Sr dynamics in the forest ecosystems are discussed.

Dynamics of 137Cs in the forests of the 30-km zone around the Chernobyl nuclear power plant.

Dynamics of the 137Cs content in the components of the forests in the 30-km zone around the Chernobyl nuclear power plant (NPP) in 1986-1994 are associated mainly with such factors as the size of radioactive particles in the fallout, ecosystem humidification and soil type, tree age. The influence of particle size was especially noticeable between 1986-1987 and was displayed by low biological availability of radionuclides in the near part of the zone (within the 10-km radius circle around the NPP) in comparison with more distant regions (within the 30-km radius circle). Later, the expression of this influence decreased and transfer factor (the ratio of 137Cs content in overground phytomass to the soil contamination density) became approximately the same for all plots with similar ecological and fallout characteristics. Humidity of landscape and soil type determined the velocity of radionuclide vertical migration in the soil and 137Cs biological availability. These parameters were maximum for the hydromorphic soils of wet landscapes enriched in organic substance and poor clayey minerals. Differences of 137Cs accumulation in overground phytomass of trees caused by tree age are displayed in the higher 137Cs concentration in structural parts of young trees as compared with old ones.

[The biogeochemistry of the radionuclides of the Chernobyl release in the forest ecosystems of the European portion of the CIS]. / Biogeokhimiia radionuklidov Chernobyl'skogo vybrosa v lesnykh ékosistemakh Evropeiskoi chasti SNG.

The 9-years dynamic of Chernobyl-derived radionuclides in the vegetation and soil covers of the forest ecosystems of the European part of the CIS is considered. The quantitative estimation has been done for main fluxes of Cs-137 in the forests of automorphic landscapes: influx to the vegetation, return with the litterfall, stem flow and throughfall, vertical migration in the soil profile (including intrasoil flow), and redistribution within the system of geochemically connected landscapes.

[Computerization of the research into radionuclide dynamics in the forest ecosystems contaminated as a result of the Chernobyl accident (1986-1995)]. / Komp'iuterizatsiia issledovanii dinamiki radionuklidov v lesnykh ékosistemakh, zagriaznennykh v rezul'tate Chernobyl'skoi avarii (1986-1995).

Large volume of information about radionuclide dynamics in the forest ecosystems, contaminated in the result of Chernobyl accident, was collected by MSU Radioecology Laboratory in 1986-1995. Experience of the data base creation, summarise and analysis of data, use of mathematical models and information and prognosis systems in the radioecology field are shown on the example of ECORAD.